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Two-dimensional single-valley exciton qubit and optical spin magnetization generation

ORAL

Abstract

Creating and manipulating coherent qubit states are actively pursued in two-dimensional (2D) materials research. Significant efforts have been made towards the realization of two-valley exciton qubits in monolayer transition-metal dichalcogenides (TMDs), based on states from their two distinct valleys in k-space. Here, we propose a new scheme to create qubits in 2D materials utilizing a novel kind of degenerate exciton states in a single valley. Combining group theoretic analysis and ab initio GW plus Bethe-Salpeter equation (GW-BSE) calculations, we demonstrate such novel qubit states in substrate-supported monolayer bismuthene – which has been successfully grown using molecular beam epitaxy. In each of the two distinct valleys in the Brillouin zone, strong spin-orbit coupling along with the symmetry leads to a pair of degenerate 1s exciton states with opposite spin configurations. Specific coherent linear combinations of the two degenerate excitons in a single valley can be excited with light polarizations, enabling full manipulation of the exciton qubits and their spin configurations. In particular, a net spin magnetization can be generated. Our finding opens new routes to create and manipulate qubit systems in 2D materials.

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Presenters

  • Jiawei Ruan

    University of California at Berkeley, and Lawrence Berkeley National Laboratory, Department of Physics, University of California, Berkeley, UC Berkeley

Authors

  • Jiawei Ruan

    University of California at Berkeley, and Lawrence Berkeley National Laboratory, Department of Physics, University of California, Berkeley, UC Berkeley

  • Zhenglu Li

    Lawrence Berkeley National Laboratory, University of California at Berkeley, and Lawrence Berkeley National Laboratory

  • Chin Shen Ong

    University of California at Berkeley, and Lawrence Berkeley National Laboratory, Uppsala University

  • Steven G Louie

    University of California at Berkeley, University of California, Berkeley, University Of California, Berkeley, University of California at Berkeley and Lawrence Berkeley National Lab, University of California at Berkeley; Lawrence Berkeley National Lab, UC Berkeley, University of California at Berkeley, and Lawrence Berkeley National Laboratory, UC berkeley, Lawrence Berkeley National Laboratory, Physics Department, UC Berkeley and Lawrence Berkeley National Lab, Department of Physics, University of California at Berkeley and Materials Sciences Division, Lawrence Berkeley National Laboratory, LBNL & UC Berkeley